Implement Android accessible hit testing using an IPC to the renderer process.

content/renderer/accessibility/renderer_accessibility_complete.cc

Index: content/renderer/accessibility/renderer_accessibility_complete.cc
diff --git a/content/renderer/accessibility/renderer_accessibility_complete.cc b/content/renderer/accessibility/renderer_accessibility_complete.cc
index 7d555ccbb245e68d8ec80fb39dcbd251a8253638..031d17e6c4a2b30ebdcc422c30c9146eb4bf0b9b 100644
--- a/content/renderer/accessibility/renderer_accessibility_complete.cc
+++ b/content/renderer/accessibility/renderer_accessibility_complete.cc
@@ -73,6 +73,7 @@ bool RendererAccessibilityComplete::OnMessageReceived(
                         OnScrollToPoint)
     IPC_MESSAGE_HANDLER(AccessibilityMsg_SetTextSelection,
                         OnSetTextSelection)
+    IPC_MESSAGE_HANDLER(AccessibilityMsg_HitTest, OnHitTest)
     IPC_MESSAGE_HANDLER(AccessibilityMsg_FatalError, OnFatalError)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
@@ -337,6 +338,19 @@ void RendererAccessibilityComplete::OnSetTextSelection(
   }
 }
 
+void RendererAccessibilityComplete::OnHitTest(gfx::Point point) {
+  const WebDocument& document = GetMainDocument();
+  if (document.isNull())
+    return;
+  WebAXObject root_obj = document.accessibilityObject();
+  if (!root_obj.updateBackingStoreAndCheckValidity())
+    return;
+
+  WebAXObject obj = root_obj.hitTest(point);
+  if (!obj.isDetached())
+    HandleAXEvent(obj, ui::AX_EVENT_HOVER);
+}
+
 void RendererAccessibilityComplete::OnEventsAck() {
   DCHECK(ack_pending_);
   ack_pending_ = false;